Following a landing due to a short term power loss shortly after takeoff; the pilot of a pitts S-1 t...

Narrative:

I experienced very temporary loss of power on departure and returned for landing. Upon tying down securely; the engine was hard to restart; but once started ran fine at full power. After a few full-power runs; I untied and departed; spiraling up to 5;500 ft. Experiencing no more problems; I flew southwest toward the freeway in case I did experience any problems. About 15 miles from ZZZ; I experienced temporary loss of power again; which settled into a power-on/power-off mode of about 1+ second. Using the wobble pump; changing magneto settings (normal) throttle; and mixture had no effect. Unfortunately; the power-on time wasn't sufficient to maintain altitude. About 5 miles northwest of ZZZ; I contacted the tower; declared an emergency; and told them of my problem and that I didn't think I could make the airport. There is dense population between me and the airport; and I'd rather go down on the freeway instead of amongst the houses. As I neared west of the airport (2 miles?); I felt that I could make the airport boundary if not the runway and lined up (already cleared to land!). Landing was successful; left turn on the taxiway and the engine stopped prior to making the parking ramp. Tied the airplane down; and engine stopped prior to making the parking ramp. Tied the airplane down; and same conditions at ZZZ1 occurred -- hard to start; but once started; full power was available. The aircraft was left at ZZZ until disassembly found the -6 aluminum fuel line from the fuel tank to the wobble pump worn through by contact with the left rudder pedal. It is my opinion that the hole in the fuel line was allowing air to enter the fuel system causing the sudden loss and recovery of power. It appears that alignment of the fuel lines had changed and the interference with the rudder pedal went unnoticed in subsequent conditional inspections.

Original NASA ASRS Text

Title: Following a landing due to a short term power loss shortly after takeoff; the pilot of a Pitts S-1 took off again only to suffer nearly complete loss of power in cruise. Pilot declared an emergency and landed at an enroute airport.

Narrative: I experienced very temporary loss of power on departure and returned for landing. Upon tying down securely; the engine was hard to restart; but once started ran fine at full power. After a few full-power runs; I untied and departed; spiraling up to 5;500 FT. Experiencing no more problems; I flew southwest toward the freeway in case I did experience any problems. About 15 miles from ZZZ; I experienced temporary loss of power again; which settled into a power-on/power-off mode of about 1+ second. Using the wobble pump; changing magneto settings (normal) throttle; and mixture had no effect. Unfortunately; the power-on time wasn't sufficient to maintain altitude. About 5 miles northwest of ZZZ; I contacted the Tower; declared an emergency; and told them of my problem and that I didn't think I could make the airport. There is dense population between me and the airport; and I'd rather go down on the freeway instead of amongst the houses. As I neared west of the airport (2 miles?); I felt that I could make the airport boundary if not the runway and lined up (already cleared to land!). Landing was successful; left turn on the taxiway and the engine stopped prior to making the parking ramp. Tied the airplane down; and engine stopped prior to making the parking ramp. Tied the airplane down; and same conditions at ZZZ1 occurred -- hard to start; but once started; full power was available. The aircraft was left at ZZZ until disassembly found the -6 aluminum fuel line from the fuel tank to the wobble pump worn through by contact with the left rudder pedal. It is my opinion that the hole in the fuel line was allowing air to enter the fuel system causing the sudden loss and recovery of power. It appears that alignment of the fuel lines had changed and the interference with the rudder pedal went unnoticed in subsequent conditional inspections.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	826056
Time
Date	200903
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	S-1 All Series
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	None
Component
Aircraft Component	Engine
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 10 Flight Crew Total 2000 Flight Crew Type 360
Events
Anomaly	Aircraft Equipment Problem Critical

Following a landing due to a short term power loss shortly after takeoff; the pilot of a pitts S-1 took off again only to suffer nearly complete loss of power in cruise. Pilot declared an emergency and landed at an enroute airport.